The primary objective of the Multiple Risk Factor Intervention Trial is to determine whether, for a group of men at above average risk of death from coronary heart disease, a special intervention program will result in a significant reduction in mortality from coronary heart disease. To achieve this objective a screening program will be conducted to identify approximately 12,000 men aged 35-37 who: are in a upper percentile of the distribution of risk for death from coronary heart disease based on risk factors of eleva serum cholestorol, elevated diastolic blood pressure, & cigarette smoking; do not have pre-existing definite clinical coronary heart disease, or other specified causes for exclusion; and are willing to commit themselves to a six-year intervention program.